Paper machinery



u 1933- c. R. CRAWFORD PAPER MACHINERY Filed Aug. 20, 1930 2 Sheets-Sheet l June 13, 1933. Q CRAWFORD 1,913,660

PAPER MACHINERY Filed Aug. 20, 1930 2 Shets-Sheet 2 Pam... June 13,1933

UNITED STATES PATENT "OFFICE ours -n. cmwronn, or mnnnn'rowx, one, assumes. r m BLAC'K-CLAWSON' I commmr, or HmL'roN, one, A o'onronn'rron or one PAPER MACHINERY Application filed August 20,

This invention relates to apparatus for forming a web of fibrous material such as fiber board or the like.

One object of the invention. is the provision of a fiber board forming apparatus having a single forming screen on which stock fibers are collected as it moves through a vat, and a pressure roll above the stock level of the vat for compressing the collected pulp' on the forming screen, the pressure roll being rotated at the same surface speed as the formin screen. I

Anot or object of the invention is the provision of an apparatus of the character mentioned, having a cylindrical forming screen,

and a screen surfaced pressure roll for compressing the stock fibers collected on the forming screen and for withdrawing water thereinto while compressing the fibers into a moist thick web. v

A further object is the provision of a fibrous board forming apparatus having a foramin'atedpressure roll for withdrawing water while compressing the fibers collected on the forming screen, together with a smoothing roll cooperating with the surface of the forming screen. i

. 1 Still another object is the provision of a paper board forming apparatus in which the moist web travels tangentially from the forming screen in a straight line to the nip of pressure rolls, after being compressed on the surface of the forming screen.

Other objects and advantages of the invention will be apparent from the following descriptiomthe appended claims and the accompanying drawings in which Fig. 1 is a side, elevation, shown partly insection, of a web forming apparatus embodying the present invention;

I Fig. 2 is a section on the line 2-2 of Fig.

1, parts being broken away and shown in section; and

Fig. 3 is a detail view, in section, of the forming screen. 2

Referring more particularly to the drawings, in which a preferred embodiment of the invention is illustrated, .10 designates generally a tank or vat of a fibrous board forming machine. Rotatable within the vat is a 1980. Serial No. 476,588.

forming cylinder designated enerally 11. Suitable bearings may be provided at or near opposite sides of the vat for rotatably supporting the shaft 12 of the forming cylinder, which is rotated at a suitable speed from a drlve wheel 13 or any other sultable source of power.

The vat is supplied in any suitable manner wlth fibrous stock or pulp in a rather thin fluid state, so that'the level of the pulp as in-' dicated at 17 is somewhat below the top of the vat, and preferably well below the top of the forming cylinder.

The forming cylinder, which may have a diameter of 10 or 15 feet or more, has a forammated surface, preferably inthe form of. a wire screen 18 of about fourteen inch mesh. This screen is supported on heavier circumferentially extending wires 19 as shown in Fig. 3, which in turn are supported upon transverse bars 20 to provide a rigid struclure, the bars 20 being supported at spaced intervals by annular rings or walls 21 which. project outwardly from the rigid cylindrical metal cylinder 22. The cylinder 22 is sup ported at spaced intervals by heavy hollow spokes 23 which project radially from the hollow shaft 12. Ad acent the end of each spoke 23 there-is an opening 24 in the shaft 12 and an opening 25 in the cylinder 22. A 89 number of rings or walls 26 extend radially parallel to the shaft axis between the cylinder 22 and the wire screen, dividing the pe-- riphery of the forming cylinder 11 into a large number of segmental areas each being incommunication-through the hollow spokes with a passage 28 in the forming cylinder shaft. The number of these passages 28, which extend axially of the forming cylin- I der shaft, correspond to the number of segmental areas in the periphery of the forming cylinder, and, any number of the segmental areas in the periphery of theforming c' linder may be placed under suction by suita le control of a regulating disk29 leading to a suction manifold 30 preferably atthe end of'the shaft 12. The pipe 31 which is in communication with the suction manifold 30, extends to a suction pump or the like. It will be understood that those segmental areas between the 100.

walls 26 which are below the level of the stock in the vat may be placed under suction, while suction is not applied to those so mental areas that project above the pulp leve theccontrolling disk 29 providing for the control of the suction in such a way that any desired rotation ofthe forming cylinder may take place after a articular segmental area has moved below t e surface of the stock, before suction is applied to it.

The forming cylinder rotates in a clockwise direction, see Fig. 1, art or all of the screen surface of the cylind r below the-level of the pulp being under suction, and during its rotation there is a gradual accumulation of the fibers of the stock on the formin surface as the water constituent of the stoc drains through the screen. The suction may start c at a point 33 for example so that the water flows into the forming screen from this point 1 up to where the formin screen leaves the stock in the vat, where t e collection on the surface of the forming screen will be'pos- I is 'a rotatable roll 35 which is adapted to compress the partly formed web of collected fibers on the surface of the forming screen. Preferably this roll 35 has a foraminated cylindrical surface of at least two or three feet in diameter. As shown, the-roll 35 is journaled in bearings 36 which are sup orted by arms 37 hung pivotally at 38 rom bracket supports 39, springs 40 being provided for pressing the suspended roll towards the forming screen. The springs 40 may be of such size as to create a pressure of several hundred ounds per inchroll length so that as the pup or fiber collection moves through the-nip of the rolls 11 and 35, it is compressed and some of the water extracted,

leavmg a moist thick sheet or web of matted fibers on the u wa'rdly moving surface of the forming cy inder. The surface of the pressure roll 35 is preferably a wire screen 41 supported on a suitable frame 42, of any suitable character. This pressure roll, havin a foraminated surface, and being at one si e of the forming cylinder but above the level of the stock in the vat, effectively withdraws a quantity of the water from the partly formed web, while compressing the same against the surface of the forming screen. The interior of the roll 35 maybe placed under suction if desired, but it is preferred that the water that is withdrawn into the roll should merely-flow down to the bottom of the roll by gravit and then out through its screen surface, eing returned to the vat or removed by a suitable baffle 44. It will thus be apparent that water is withdrawn from both sides of the partially formed fiber sheet on the forming cylinder, as it passes through the nip of the rolls 35 and 11. vAs previously mentioned, the diameter of the pressure roll 35 is two or three feet or more, and this roll is positively driven at the same surface or peripheral speed'as the forming cylinder 11, being connected by suitable transmission devices 46, to the driving wheel 13, so that the partly formed stock gathered and matted on the surface of the forming cylinder will not be disturbed while being compressed by the roll 35.

After passing by the pressure roll 35, the moist thick fiber sheet or web on the forming cylinder is moved along to a smoothin cylinder 47. The surface of this cylin er is preferably of rubber, although it may be made of fine wire mesh, if desired. Axle shafts 48 at the ends of the smoothing roll 47 are carried in suitable bearings 49 which are supported by springs 50 and 51. The springs 51 are adapted to support the weight 0 the roll 47 and its bearings when fully compressed, so as to maintain a minimum distance of an inch or two depending upon the desired thickness of the fiber board, between the peripheries of the smoothing roll 47 and the forming cylinder 11. The springs 50 exert a controlled pressure downwardly upon the roll 47 this pressure being governed by hand-wheels 53 so that a pressure of several hundred pounds per inch roll length may be applied to the moist fiber sheet on the forming cylinder. If a mass of pulp of extra large thickness should come up to the smoothing roll 47 it can move upwardly .in a yielding manner due-to its spring support, permitting the large mass of pulp to pass through. The roll 47 smooths out the surface of the web, which may be ridged or grooved by the foraminated surface of the roll 35, and alsoserves to further compress and force water from the web so it may leave the nip of the roll 47 in. a semi-ri id state and dry enough to be practically se f-sustaining.

The smoothing pressure roll 47 is located preferably centrally above the forming cylinder so that the moist board web leaves the forming cylinder tangentially in a substantially horizontal direction, and travels in a straight line to a series of press rolls 55. These press rolls are provided in pairs, as shown, so that the board web 56 passes through the press rolls in a straight line, thus avoiding any bends in the web from the time it leaves the nip of the roll 47 until it is compressed and further dried by the press rolls 55, which leave the sheet 1n a practically rigid stifi condition. Heretofore the part1? formed sheet when leaving the forming cy inder has not been moved in a straight line tangentially from the forming cylinder and consequently the bends that obtain in the sheet loosened the formation and weakened the sheet as the matted condition of the fibers was disturbed. In accordance with the present invention however, this objectionabledefect of the prior practice is entirely obviated and the final product is very strong and of a dense and homogeneous character.

It will be apparent that all of the fibers of the finished board will be closely interwoven and intimately held together as the board web leaves the forming cylinder, as there is only a single forming screen subjected to the stock, and there will be no tendency for the board to split centrally as might be the case if two forming screens were used in conjunction'to press two separate portions of collected fiber mats together. The withdrawal of water from both sides of the partly formed web, that obtains at the nip of the screen surfaced pressure roll and the forming cylinder 11 is so effective that a smoothing .roll such as the roll 47 need not be employed,

this roll 47 being particularly useful however to smooth the surface of the sheet and to further compress the sheet and further dry the same. The smoothing roll 47 is preferably driven by a suitable transmission or drive 58 so that it moves at the same surface speed as the forming cylinder, and thus it will not disturb the surface of the formation of the wet sheet that it engages.

While the form of ap aratus herein described constitutes a pre erred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be inder, a rotatable pressure roll having a foraminated surfacecooperating with the upwardly moving portion of said forming screen at one side of the forming screen near the stock level of the vat, said pressure roll being adapted to withdraw water. thereinto while compressing the collected fibers agalnst the forming screen, a smoothing roll cooperating with the topof the forming screen, and pressure rolls for compressing the board web after it leaves the forming screen and so arranged that the board web comes to the nip of said pressure rolls ina substantially straight line substantially'tangentially from the forming screenand the smoothing roll. Y

2. Web forming apparatus of the class depressing the fibers against the forming cylinder, means for positively driving said pressure roll and sa1d forming cylinder at the same peripheral speed, and pressure rolls for compressing the fibrous web after it leaves the forming cylinder and so arranged that the fibrous web comes to the nip of said pressure rolls in a straight line substantially tangentially from the forming cylinder.

3. Web forming apparatus of the class described comprising a stock vat, a forming cylinder for said vat having a foraminated surface on which stock fibers are collected, a rotatable pressure roll above the pul level of the vat havin a foraminated sur ace cooperating with t e surface of theformin cylinder for compressing the fibers col ected thereon, said pressure roll cooperating with an upwardly moving side of said forming cylinder, a second pressure roll above said forming cylinder having a smoothing surface cooperating with the forming cylinder, and means for driving said forming, cylinder said rotatable pressure roll and said secon pressure roll at the same eripheral speed.

4. Apparatus for manufacturing fibrous board comprising a stock vat, a forming screen for said vat on which stock fibers are collected, a pressure roll cooperatin with the surface of the forming screen, an ressure rolls for com ressing the board we after it leaves the ormin screen and so arran ed that the board weh comes to the nip of sai pressure rolls in a straight line tangentially from the formin screen and tangentially from the first sai pressure roll.

5. Apparatus for manufacturing fibrous board comprisin 'a stock vat, a cylindrical forming screen or 'said vat on which stock fibers are collected, a pressure roll cooperating with the surface of the forming screen, and pressure rolls arranged in pairs for compressing the board web after it leaves the orming screen and so arranged that the board web comes to the nip of said pressure rolls in a straight line tangentially from the forming screen and tangentially from the first said pressure roll.

In testimony whereof I hereto afiix my signature.

-CLIFlT R. CRAWFORD. 

